Who dives both PDC & SPG?

[RJP]

I dive a Suunto Vytec DS with transmitter and an SPG plus a Uwatec bottom timer on my other wrist.

Part of this is simple "belt and suspenders" redundancy in case the computer craps out. But another reason to go this route is that I dive doubles so I need/like to be able to know the pressure in either tank if I should have to isolate by closing the manifold.

So I have the transmitter on my right post with the Vytec DS on my right wrist. The SPG comes off the left post and is clipped to left hip d-ring, with the Uwatec bottom timer on the left wrist. Keeping left/left and right/right together helps make it more intuitive to remember what's reading pressure where, especially if the dive has gone south.

When diving singles on vacation I will bring the SPG in my bag, but not hook it up unless I need it. I still dive with both the Vytec DS and the Uwatec on vaction/singles. This way, if the Vytec should crap out I still have depth and time and my last 10 dives on the Uwatec. If that does happen I swap the transmitter out for the SPG, pull out my tables and I'm ready to go without missing a dive.

 

[spectrum]

My computer is not air integrated and I have no interest in relying on underwater electronics, let alone transmitters for that information, I also have better things to do with my money. If one chosses to be air integrated analog backup gauges are suggested.

Another perspective is that if the air integration ever craps out it's time to end the dive, no big deal. You should already know that you are not in peril. This works for modest non-overhead dives. If it goes out on a vacation or significant dive that stinks.

Streamlining is way overrated when people start worrying about hoses.

Pete

 

[jd950]

I have an Oceanic wrist computer that is air integrated. I find it very convenient to have all the information I need on my wrist as I frequently have a camera while diving and just need to move my arm slightly to see what I need. I have only lost the link once (that I know of) when I had the camera extended way out to take a shot at a weird angle. I brought my wrist in close to my shoulder and the link was immediately restored.

Still, I have a compact SPG attached to a D ring on my left side. If I should have a computer crash or a dead transmitter battery, etc., I then have a backup. It was not expensive and is not in the way, so why not?

I also take a non-AI computer along with me so at any time if something should break, die, get lost or stolen, I don't have to end the dive or resort to tables for the next dives.

Compared to the cost of airfare, hotels, boats and dive masters, its a small price to pay for some insurance.

 

[Walter]

What is a PDC?

 

[mikeguerrero]

What is a PDC?

PDC = Personal Dive Computer (Digital)

SPG = Standard Pressure Gauge (Analog)

 

[Doc Intrepid]

What is a PDC?

As opposed to "Group Dive Computer"?

Or "Impersonal Dive Computer"?

(One keeps your secrets, the other doesn't care...)



I was confounded also...

 

[mikeguerrero]

All your input has been great and after much thought I feel I'll keep my pony gauge. I feel it's very important to have your dive buddy knowledgeable on all your equipment and that means knowing how to read my pony gauge.

If and when my transmitter stops communicating with my PDC, I'll have my dive buddy check my first stage and read my PSI left. Upon acknowledgement of my air left in my tank I will make the call to ascend to my safety stop and end my dive. (I'm talking about ending my dive as my transmitter can no longer transmit)

I've read from a lot of divers that the PDC sometimes loses it's signal for small intermitted seconds throughout the shift in your arm in accordance to distance from the transmitter. As long as the unit picks back up you are okay to continue your dive.

I personally don't stay glued to my PSI throughout my dive, I'm not watching the news where if I break away for a couple of seconds I may miss important data.

I periodically glance at it like a rearview mirror while driving or even the fuel tank as I'm getting low on gas in my car and I'm traveling a long highway.

I also agree with a lot of divers that when things feel less than perfect, there is reason to abort the dive. No need to continue doing a dive only for matters to go from bad to worse.

There are many other days you can go back to more than perfect conditions for diving.

Let me tell you why I started this thread:

This past weekend I wanted to go diving but my dive partner had plans for Vegas. Feeling the urge to try out my new PDC and dial in my weights to my new steel tank I placed an add on scubaboard and before you new it, I had an instant dive buddy.

Cautious because my diving time is newbee and my intant buddy is advanced, I let his group know and he was considerate and said he'd still welcome me to dive with them.

I arrived at Break Water to find conditions really nice about 20+ feet vis in the morning, however by the time he got to BW the conditions were horrible.

As a unit we all agreed to continue the dive and made a dive plan towards the Metridiums to evade the red tide and head back.

I got all my equipment in order, suited up and ready to make this dive. All systems were green and when I went to link up my PDC to it's transmitter it would not link no matter what I did. My instant buddy even came over and tried to help me out, since he also owned a PDC only his was different brand.

After playing around with it and running up and down in my wetsuit to retreive a new set of batteries I still came up short; frustrated beyond words I scrubed my dive.

I did not have a backup SPG nor did I really want to dive after not having my computer link up.

Later I learned via Oceanic (awesome customer support) the next day that I had wiped out my transmitter code when I linked up the PDC to my lap top the night before. I had set up the time and date the night before and by mistake deleted the transmitter code. So when I downloaded the data back to the PDC, she took in a blank code and wouldn't start.

I learned from my experience why NASA scubs missions when something as trivial as weather doesn't match launch conditions.

Diving is no different, if you have less than perfect diving conditions and some of your equipment is not all tunned in before the dive, why place yourself against greater elements? I certainly learned that if my PDC is not ready and it has many safety features that let the diver know prior to any dive; not to commence, I will not dive.

My pony gauge is a nice feature that tells me my diving PSI prior to my linking up my PDC. If conditions match I'm go for the dive, if not something is wrong and worth fixing.

Once into my dive and my PDC goes dead on transmitting PSI, it's time to have my dive partner check my PSI on my first stage via the pony gauge. I then should make the call to return to the surface.

MG

 

[1gromit]

cheers,

By and large, I agree with your reasoning. However, why not just go with a full spg, not just the pony? why create a situation which, by default, requires someone else to help you?

I dive the Aeris AI equiv of your VT3 (virtually the same internals). I d-ring a retractor with mini-pressure gauge to my bcd (it's tiny but quite readable), and wear a citizen dive watch on my non-pdc wrist that has depth and time.

Like you, I'm never glued to my gauges, and it doesn't bother me at all if the computer loses sync with the transmitter for brief periods (tho, in fact, it never has). True, I rarely look at the mini-pressure gauge, no more than twice per dive, sometimes only once a dive. Still, it's interesting to see the variability between equipment. A scubapro certified technician once told me that it's common to see 100-250 psi differences between pressure gauge readings, and 2-4 ft between depth gauges. I was shocked at the variability. But I will say this, there was a 8 ft difference b/w my old scubapro pdc and my made-in-italy scubapro spg. Based on the average of other diver's equipment, I determined that the pdc was correct and the spg erroneous. I ditched it, replaced it with the mini-spg I use now.

Al

 

[Colliam7]

As several others, I dive a SPG clipped to a (waist) D-ring, along with a PDC (Vytec) with transmitter. It is simply convenient to check my air on my wrist. The AI is generally reliable, but every once in a great while doesn't sync, or loses the connection at lower pressures (<1000). In those cases, I have the backup and it doesn't affect the dive.

 

[CompuDude]

cheers,

By and large, I agree with your reasoning. However, why not just go with a full spg, not just the pony? why create a situation which, by default, requires someone else to help you?

I dive the Aeris AI equiv of your VT3 (virtually the same internals). I d-ring a retractor with mini-pressure gauge to my bcd (it's tiny but quite readable), and wear a citizen dive watch on my non-pdc wrist that has depth and time.

I agree. I have a wireless AI computer, and wear a plain brass n'glass SPG on a short hose clipped off to my left hip. Never even know it's there, and yet, it's there if I need it, and it doesn't make me dependent on someone else to check.

The pony gauge is cute, but I'd rather have a full size one that doesn't require someone else to allow it to function, when there's such a simple alternative available.